The Arctic Low-Level Mixed-Phase Haze Regime and its Microphysical Differences to Mixed-Phase Clouds
Year: 2026
Type: article
Abstract: A comprehensive in-situ dataset of low-level Arctic clouds was collected in the Fram Strait during the HALO-(AC) 3 campaign in spring 2022 using the research aircraft Polar 6. The clouds observed at altitudes below 1000 m were frequently in a mixed-phase state. We demonstrate that despite comparable optical properties, classic mixed-phase clouds (MPC) and mixed-phase haze (MPH) can be distinguished on the basis of their microphysical properties, with MPH observed about 8 times more frequently than MPC. While the thermodynamic phases of the particles within the MPH are similar to those in the MPC, the supercooled droplets observed in MPC are replaced by large (> 3 µm) wet aerosol particles in MPH. Furthermore, the particle number concentration measured in MPH is reduced by approximately 3 orders of magnitude compared to MPC. MPH is observed in subsaturated air with respect to water, suggesting that the small liquid particles are haze droplets and are in equilibrium below the activation threshold to form cloud droplets. Chemical analysis suggested that the haze particles contained significant amounts of sea salt. Additional in-situ measurements with an optical particle counter indicated that their number concentration was 2 times larger over the sea ice compared to the open ocean. Furthermore, measurements of the vertical distribution of the thermodynamic phases in low-level Arctic clouds revealed a characteristic structure, with a liquid regime frequently occurring at the top of the atmospheric boundary layer, followed by MPCs, and an MPH layer below. The findings from this study enhance our understanding of the microphysical composition of clouds in mixed-phase conditions.
Authors: Manuel Moser, Christiane Voigt, Oliver Eppers, Johannes Lucke, Elena De La Torre Castro, Johanna Mayer, Regis Dupuy, Guillaume Mioche, Olivier Jourdan, Hans-Christian Clemen, Johannes Schneider, Philipp Joppe, Stephan Mertes, Bruno Wetzel, Stephan Borrmann, Marcus Klingebiel, Mario Mech, Christof Lüpkes, Susanne Crewell, André Ehrlich, Andreas Herber, Manfred Wendisch
Institutions: Deutsches Zentrum für Luft- und Raumfahrt e. V. (DLR), Johannes Gutenberg University Mainz, Max Planck Institute for Chemistry, Delft University of Technology, Université Clermont Auvergne, Laboratoire de Météorologie Physique, Leibniz Institute for Tropospheric Research, Leipzig University, University of Cologne, Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung
Language: English
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,725
Awards: G135623947, Microphysical Process Characterization of Mixed Phase Clouds in the European Arctic, G3653964306, Koordinationsfonds, G434337789, TRR 172: Arktische Verstärkung: Klimarelevante Atmosphären und Oberflächenprozesse und Rückkopplungsmechanismen (AC)3, SENSors and certifiable hybrid architectures FOR safer aviation in ICing Environment, TRR 301: Die Tropopausenregion in einer Atmosphäre im Wandel, Messung von Aerosol und Wolken und deren Wechselwirkung über dem sauberen Südlichen Ozean (AWWSO), Messungen von Aerosolpartikeln und Wolkenresiduen in hohen Breiten im Rahmen der HALO2020Mission CIRRUSHL: Partikelzusammensetzung und Wechselwirkungen mit Zirruswolken, G8448705601
OpenAlex ID: W7128047170